GIS for Gettysburg Battlefield Planning and Rehabilitation

Landscape Rehabilitation	Borough Growth

Battle of Gettysburg troop movement, troop positions, and battle action were mapped from after-action reports, letters, diaries, and newspaper accounts. Landscape features significant to the outcome of the battle were mapped using military engineering terrain analysis techniques. This involved evaluation of the terrain based on a set of five characteristics—key terrain, observation and fields of fire, cover and concealment, obstacles, and avenues of approach (KOCOA). Based on the KOCOA map and the battle action maps, a major battle action resource management area was identified. Landscape features within this area that changed between 1863 and the present are scheduled for rehabilitation within the next five years.

Landscape rehabilitation at the Gettysburg National Military Park has been guided by a variety of maps and documents that have been integrated using GIS tools. Highly detailed topographic maps drawn at a scale of 1:2,400 in 1869 by the United States Army Corps of Topographic Engineers were scanned and georeferenced in ArcGIS. Displaying these maps as transparent layers over current basemaps and satellite imagery makes it possible to see how the historic battlefield features, such as fences, lanes, orchards, fields, and woodlots, have either changed or been removed. Geometric calculations that result from these overlays provide the information needed by managers to determine how many trees to order for planting, how much fence to rebuild, and the acreages of fields and woodlots that need cutting to restore and maintain their 1863 appearance.

Gettysburg National Military Park’s Resource Planning Division also uses GIS to assist with community planning in the neighborhood of the park. The growth of the borough of Gettysburg since the time of the battle in 1863 is shown in a map that was prepared as a part of the development of the borough’s new interpretive plan. On this map, the borough’s buildings have been color coded according to the era in which a house was first built in that location.